1. Field of the Invention
This invention relates to apparatus for filling the cells of an expanded cellular core member with granular insulation, and more particularly to improvements in such apparatus.
2. Description of the Prior Art
Expanded cellular core members, such as honeycomb core members, are used extensively in building panels in the form of sandwiches wherein facing sheets are bonded by glue layers to the opposite faces of the honeycomb core member. See for example U.S. Pat. Nos. 2,556,470 (DEL MAR); 2,839,442 (WHITAKER); 2,849,758 (PLUMLEY et al); 2,893,076 (HERTS); 2,911,076 (SAUNDERS et al); 3,817,810 (RONAN et al). Honeycomb sandwiches exhibit poor thermal insulating and sound attenuating characteristics. To improve these characteristics, the cells of the honeycomb core have been filled with materials, such as a compressed fibrous and resin-containing mixture, see U.S. Pat. Nos. 3,630,813 (ALLEN); 3,733,229 (SCHEER et al); or with granular insulation, such as perlite, see SAUNDERS et al, supra; and copending U.S. patent applications Ser. No. 601,296 (FRANDSEN) and Ser. No. 601,342 (ANDERSON) both filed Aug. 4, 1975, now U.S. Pat. Nos. 3,998,024 and 3,998,023 respectively and both assigned to the assignee of this invention.
Where a film of adhesive material is provided on the upper ends of the cells prior to filling the cells with insulation, a reliable final bond between the facing sheet and the core member can only be achieved if the film of adhesive and the surface to which the adhesive is subsequently adhered is substantially entirely free of the insulation. After the cells have been filled, rendering the film of adhesive substantially entirely free of insulation while maintaining the cells uniformly filled is difficult to achieve. The friability of granular insulations, in particular perlite, is bothersome.